package com.ctrlspace.core.util;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Security {
	/**
	 * Computes the SHA-1 hash value for the given text.
	 * 
	 * Computes the SHA-1 hash value for the given text. Code taken from
	 * 
	 * 		http://www.anyexample.com/programming/java/java_simple_class_to_compute_sha_1_hash.xml
	 * 
	 * @param text the text to get the hash value for
	 * @return the SHA-1 hash value for the given text
	 * @throws NoSuchAlgorithmException
	 * @throws UnsupportedEncodingException
	 */
	public static String SHA1(String text) {
		MessageDigest md = null;
		try {
			md = MessageDigest.getInstance("SHA-1");
			
			byte[] sha1hash = new byte[40];
			md.update(text.getBytes("iso-8859-1"), 0, text.length());
			sha1hash = md.digest();

			return convertToHex(sha1hash);
		} catch (NoSuchAlgorithmException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return null;
	}

	private static String convertToHex(byte[] data) {

		StringBuffer buf = new StringBuffer();
		for (int i = 0; i < data.length; i++) {
			int halfbyte = (data[i] >>> 4) & 0x0F;
			int two_halfs = 0;
			do {
				if ((0 <= halfbyte) && (halfbyte <= 9))
					buf.append((char) ('0' + halfbyte));
				else
					buf.append((char) ('a' + (halfbyte - 10)));
				halfbyte = data[i] & 0x0F;
			} while (two_halfs++ < 1);
		}
		return buf.toString();
	}
}
